1. Field of the Invention
This invention can be applied to apparatuses such as a printer, a copying machine, a facsimile apparatus such as a communication system and a word processor having a printer portion for effecting recording on a recording medium such as paper, yarn, fiber, cloth, metals, plastics, glass, wood or ceramics, and further an industrial recording apparatus compositely combined with various processing apparatuses.
The term xe2x80x9crecordingxe2x80x9d in the present invention means not only imparting meaningful images such as characters and figures to a recording medium, but also imparting meaningless images such as patterns to a recording medium.
2. Related Background Art
There is known an ink jet recording method, i.e., a so-called bubble jet recording method, of imparting energy such as heat to ink to thereby cause a state change resolution from a steep volume change (creation of a bubble) to the ink, discharging the ink from a discharge port by an acting force based on this state change of the ink, and causing the ink to adhere to a recording medium to thereby effect image formation. In a recording apparatus using this bubble jet recording method, as disclosed in U.S. Pat. No. 4,723,129, there are generally disposed a discharge port for discharging ink therefrom, an ink flow path communicating with this discharge port, and an electro-thermal converting member as energy generating means for discharging the ink disposed in the ink flow path.
According to such a recording method, images of high dignity can be recorded at a high speed with low noise and in a head carrying out this recording method, discharge ports for discharging the ink can be disposed highly densely and therefore, there are many excellent advantages that recorded images of high resolution and further, color images can be easily obtained by a compact apparatus. Therefore, in recent years, this bubble jet recording method has come to be utilized in many office machines such as printers, copying machines and facsimile apparatuses, and further in an industrial system such as a textile printing apparatus.
As the bubble jet technique is thus utilized in products in many fields, the following various requirements have been further rising in recent years.
For example, as the examination of the requirement for improved energy efficiency, mention is made of the optimization of a heat generating member such as the adjustment of the thickness of the protective film of the heat generating member. This technique is effective in improving the propagation efficiency of generated heat to liquid.
Also, in, order to obtain images of high quality, there has been proposed a driving condition for giving a liquid discharging method in which the discharge speed of ink is high and which can accomplish good ink discharge based on the stable creation of bubbles, and from the viewpoint of high speed recording, there has been proposed an apparatus improved in the shape of a liquid flow path to obtain a liquid discharge head in which the refill speed of discharged liquid into the liquid flow path is high.
FIGS. 9A and 9B of the accompanying drawings are a top plan view and a cross-sectional view, respectively, of the essential portions of a liquid discharge head according to the prior art.
A movable member 106 supported on and fixed to an element substrate 100 by a fixing portion 106d is formed so that the free end 106b of a movable portion 106c may be displaced in the direction of arrow A with a root 106a as a fulcrum.
The upper surface side of the movable member 106 is a liquid flow path which is the flow path of ink, and arrow B indicates the direction in which the ink flows. A heat generating member 102 is formed generating energy for creating a bubble in the ink, and the bubble is created on the upper surface of the heat generating member 102. By this bubble, the free end 106b of the movable member 100 is displaced upwardly and the ink is discharged from a discharge port, not shown.
The present invention has as its main task to basically enhance the fundamental discharge characteristic of a conventional method of forming a bubble, particularly, a bubble resulting from film boiling, in a liquid flow path to thereby discharge liquid to a level which could heretofore not be anticipated.
We have eagerly studied to provide a novel liquid drop discharging method utilizing bubbles which could heretofore not be obtained, and a head, etc. using the method. At this time, we have carried out a first technical analysis starting from the operation of a movable member in a liquid flow path such as analyzing the principle of the mechanism of the movable member in the liquid flow path, and a second technical analysis starting from the principle of the liquid drop discharge by a bubble, and further a third analysis starting from the bubble forming area of a heat generating member for forming bubbles, and by these analyses, we have come to establish quite a novel technique for bringing the disposition relation between the fulcrum and free end of the movable member into a relation in which the free end is located at the discharge port side, i.e., the downstream side, and disposing the movable member in face-to-face relationship with the heat generating member or the bubble creating area thereof to thereby positively control the bubbles.
Next, we have come to the knowledge that when considering the energy a bubble itself gives to the amount of discharge, it is the greatest factor for being capable of markedly improving the discharge characteristic to consider the growth component at the downstream side of the bubble. That is, it has also been found that it brings about improvements in the discharge efficiency and the discharge speed to efficiently convert the growth component at the downstream side of the bubble into the discharge direction.
Further, it has been found that it is also preferable to take into account structural elements such as the movable member and the liquid flow path concerned in the growth in the heat generating area for forming a bubble, e.g., the downstream side from the center line passing through the center of the area of an electro-thermal converting member in the direction of flow of the liquid, or the downstream side of the bubble such as the center of the area on a surface which governs bubbling.
However, when durability has been confirmed on this liquid discharge head, there has been the problem that at the initial stage, the root 106a of the movable portion 106c shown in FIG. 9B is first broken away.
So, the present invention has as its object to provide a liquid discharge head for discharging liquid by the utilization of the displacement of the free end of a movable member by pressure based on the creation of a bubble, which is improved in the durability of the movable member and is stable in discharge characteristic and high in reliability, and a liquid discharge apparatus.
To achieve the above object, the liquid discharge head of the present invention is a liquid discharge head having an element substrate on the surface of which are provided in parallel a plurality of discharge energy generating elements generating heat energy for creating a bubble in liquid, a fixed portion provided on said element substrate so as to face said plurality of discharge energy generating elements, and fixed to said element substrate, and a plurality of movable members comprising a movable portion extending from the end portion of said fixed portion and displaced by said bubble, wherein a fulcrum about which said movable portion is displaced is located on said movable portion other than a corner portion formed at the boundary between said movable portion and said fixed portion.
In the liquid discharge head of the present invention constructed as described above, the fulcrum of the movable portion is formed on the other portion than the corner portions. Thereby, the concentration of stress to the corner portions is avoided.
The plurality of movable members may be of a construction in which they are connected together at the position of the fulcrum, and the movable members may be formed of silicon nitride.
The liquid discharge head of the present invention is a liquid discharge head having an element substrate on the surface of which are provided in parallel a plurality of discharge energy generating elements generating heat energy for creating a bubble in liquid, a fixed portion provided on said element substrate so as to face said plurality of discharge energy generating elements, and fixed to said element substrate, and a plurality of movable members comprising a movable portion extending from the end portion of said fixed portion and displaced by said bubble, characterized in that the shape of the fixed portion is a shape which expedites stress dispersion for preventing stress from concentrating on particular one of the movable members.
The liquid discharge apparatus of the present invention has a carriage removably holding the liquid discharge head of the present invention thereon, and supported for reciprocal movement along the surface of a recording medium, and discharges liquid from the liquid discharge head of a head cartridge to thereby effect recording on the recording medium.